Gas sealing valves



United States Patent Inventor John Dougall Harlow, England Appl. No. 739,443 Filed June 24, 1968 Patented Aug. 11, 1970 Assignee Associated Electrical Industries, Limited London, England a British company Priority June 27, 1967 Great Britain 29,627/67 GAS SEALING VALVES 3 Claims, 3 Drawing Figs.

0.8. CI 137/269, 251/176 Int. Cl Fl6k 51/00 Field of Search 251/176,

11 12 7P 7 14 i? I Primary Examiner- Henry T. Klinksiek Assistant Examiner- Robert J. Miller Attorney-Larson and Taylor ABSTRACT: A two way gas sealing valve between aligned apertures in parallel walls comprises a pair of plates laterally movable across the plates and spring pressed apart with means for holding the plates away from the walls except when they are aligned with the apertures when they are released to engage seatings around the apertures.

FIGI

r/V/A Patented. Aug. 11, 1970 GAS SEALING VALVES BACKGROUND OF THE INVENTION This invention relates to gas sealing valves and more particularly to double acting valves.

The invention has important application in valves for vacuum systems. It is known to effect a gas seal by means of a plate which is moved to cover an aperture and is pressed against a seating around the aperture by the pressure difference on opposite sides.

Such a construction relies on the pressure difference to maintain the seal and is hence only effective in one direction.

If sealing in two directions is required it is necessary either to provide two separate valves or to locate the plate between seals around apertures in opposite walls. In order to effect the sealing the seals must press against the plate with considerable pressure and this means that considerable mechanical force must be exerted to move the plate and this is liable to damage the seals.

The main object of the invention is to provide a double acting plate type valve which substantially avoids the above disadvantages.

SUMMARY OF THE INVENTION According to the present invention a double acting valve for closing aligned apertures in a pair of parallel walls comprises a pair of parallel plates interconnected to move in unison along guides between valve open and valve closed positions, the guides extending substantially parallel to and between said walls, spring means pressing the plates apart and the guides being so arranged that they hold the plates clear of the respective walls except when aligned with the apertures in which position the guides release the plates to allow the spring means to force the plates against seatings around the respective apertures.

According to one arrangement selective control means may be provided whereby either plate may be prevented from closing to render the valve single acting.

According to another arrangement means may be provided for applying a rough vacuum to the space between the valve openings to allow the plates to lift from the seating when the valve is in the close position, and one of the vacuums has been broken.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be more clearly understood reference will now be made to the accompanying drawings in which:

FIG. I is a section, assumed for purposes of description to be a horizontal section of one embodiment of the invention,

FIG. 2 is a cross-section on the line lI-ll of FIG. I, and

FIG. 3 is a section corresponding to FIG. I but showing another embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. I the references 1 and 2 indicate two walls in which are openings 3 and 4 respectively, the walls 1 and 2 are joined by the end walls 5 and 6.

The apertures 3 and 4 can be closed by the plate closure members 7 and 8 respectively, these are pressed apart by springs 9, guide pins 10 retaining their relative positioning, and have wheels 11 running along guide rails 12 having extensions 13.

In the position shown in FIGS. l and 2, which is the valve open position, the guide rails hold the plate closure members 7 and 8 clear of the walls I and 2 respectively, when however the plates are moved to the right to the closed position by means of the actuating rod, the wheels 11 run down ramp surfaces 14 on the ends of the rails into gaps in the rails, and the plate closure members are forced apart by the springs 9, so that they press against seals, such as 0' rings 15 around the respective apertures and close the apertures.

In order to re-open the valve the plates are moved to the left, the wheels first run up the ramp surfaces so that they are lifted away from the seals beforethe movement proper starts.

It will be appreciated that with the apparatus shown, both apertures 3 and 4 may be opened and closed simultaneously, however, conditions may arise in which it is only desired to close one of the apertures, and this result may be achieved by the stop members 16 which are in effect rail extensions and prevent the plates abutting against the seals in the valve closed position. The stop members 16 are mounted on spindles 17 which can be rotated by handles 18 from outside the casing so that the stop members 16 may either be positioned as shown in full line in FIG. I to maintain the aperture 4 open or alternatively the stop members may be positioned as shown dotted to keep the aperture 3 open. In addition of course the members may be moved to a mid position in which neither aperture is kept open.

FIG. 3 shows an alternative embodiment of the invention in which the selector apparatus is omitted, the apertures 3 and 4 provide communication between a central chamber 19 and a pair of side chambers 20 and 21 respectively.

It follows that when the valve is actuated to the valve closed position both plates will close simultaneously. If now the vacuum in either the chamber 20 or the chamber 21 is broken say that in chamber 20 the pressure difference will tend to force the plate concerned, i.e. plate 7, off its seating so that the vacuum in the central chamber 19 is broken, the plate 8 will be held on its seating by the spring pressure.

On re-evacuation it is not possible to open the plate 8 because it is held against its seating by the combined action of the spring pressure and the gas pressure difference across it. This is overcome by applying a roughing vacuum to the chamber 19.

In the arrangement shown the roughing vacuum is applied by connecting a vacuum pump 24 through a roughing valve 22 to the chambers 20, 19 and 21 selectively.

For example, either the chambers 20 and 19 could be connected to the vacuum pump through the lines 27 and 26, or the chambers 21 and 19 could be connected to the pump through the lines 25 and 26. In this way the valve can always be opened for evacuation purposes.

Iclaim:

l. A double acting valve comprising:

a pair of parallel walls,

edges in said walls defining aligned apertures,

valve seatings around said apertures,

a pair of parallel valve plates located between the walls and movable parallel to said walls between valve closed and valve open positions, guides along which the plates are movable and which normally retain the plates laterally clear of the walls,

interconnections between the plates whereby they move in unison,

spring means pressing the plates apart ramp surfaces to said guides whereby in the valve closed position the guides allow the springs to press the valve plates against the seatings.

2. A double acting valve as claimed in Claim 1 comprising:

selective control means whereby either plate may be prevented from closing to render the valve single acting.

3. In vacuum apparatus comprising chambers adapted to be evacuated and separated by a pair of spaced parallel walls:

edges in said walls defining aligned apertures,

valve seatings around said apertures.

a pair of parallel valve plates located between said walls and movable parallel to said walls between valve open and valve closed positions.

guides along which the valves are movable and which are positioned normally to retain the plates clear of the seatings,

interconnections between the plates whereby they move in unison.

spring means pressing the plates apart,

ramp surfaces and gaps in said guides whereby in the valve closed position the guides allow the springs to press the valve against the seatings, and means for applying an ad- 

